Giant Spin Transfer Torque in Atomically Thin Magnetic Bilayers
Weihao Cao1,2, Matisse Wei-Yuan Tu1,3*, Jiang Xiao4,5, and Wang Yao1,3*
1Department of Physics, University of Hong Kong, Hong Kong, China 2Department of Physics, University of California San Diego, La Jolla, CA 92093-0319, USA 3HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China 4Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China 5Institute for Nanoelectronics Devices and Quantum Computing, Fudan University, Shanghai 200433, China
Abstract：In cavity quantum electrodynamics, the multiple reflections of a photon between two mirrors defining a cavity is exploited to enhance the light-coupling of an intra-cavity atom. We show that this paradigm for enhancing the interaction of a flying particle with a localized object can be generalized to spintronics based on van der Waals 2D magnets. Upon tunneling through a magnetic bilayer, we find that the spin transfer torques per electron incidence can become orders of magnitude larger than $\hbar /2$, made possible by electron's multi-reflection path through the ferromagnetic monolayers as an intermediate of their angular momentum transfer. Over a broad energy range around the tunneling resonances, the damping-like spin transfer torque per electron tunneling features a universal value of $(\hbar/2)\tan (\theta /2)$, depending only on the angle $\theta$ between the magnetizations. These findings expand the scope of magnetization manipulations for high-performance and high-density storage based on van der Waals magnets.
Huang B, Clark G, Navarro-Moratalla E, Klein D, Cheng R, Seyler K, Zhong D, Schmidgall E, McGuire M, Cobden D, Yao W, Xiao D, Jarillo-Herrero P and Xu X 2017 Nature546 270
[8]
Gong C, Li L, Li Z, Ji H, Stern A, Xia Y, Cao T, Bao W, Wang C, Wang Y, Qiu Z Q, Cava R J, Louie S G, Xia J and Zhang X 2017 Nature546 265
[9]
Deng Y, Yu Y, Song Y, Zhang J, Wang N Z, Sun Z, Yi Y, Wu Y Z, Wu S, Zhu J, Wang J, Chen X H and Zhang Y 2018 Nature563 94
[10]
Fei Z, Huang B, Malinowski P, Wang W, Song T, Sanchez J, Yao W, Xiao D, Zhu X, May A, Wu W, Cobden D, Chu J and Xu X 2018 Nat. Mater.17 778
[11]
Lee J U, Lee S, Ryoo J H, Kang S, Kim T Y, Kim P, Park C H, Park J G and Cheong H 2016 Nano Lett.16 7433
[12]
Wang X, Du K, Yang Y, Liu F, Hu P, Zhang J, Zhang Q, Owen M H S, Lu X, Gan C K, Sengupta P, Kloc C and Xiong Q 2016 2D Mater.3 031009
[13]
O'Hara D J, Zhu T, Trout A H, Ahmed A S, Luo Y K, Lee C H, Brenner M R, Rajan S, Gupta J A, McComb D W and Kawakami R K 2018 Nano Lett.18 3125
[14]
Bonilla M, Kolekar S, Ma Y, Diaz H C, Kalappattil V, Das R, Eggers T, Gutierrez H R, Phan M H and Batzill M 2018 Nat. Nanotechnol.13 289
Song T, Cai X, Tu M W Y, Zhang X, Huang B, Wilson N P, Seyler K L, Zhu L, Taniguchi T, Watanabe K, McGuire M A, Cobden D H, Xiao D, Yao W and Xu X 2018 Science360 1214
[17]
Klein D R, MacNeill D, Lado J L, Soriano D, Navarro- Moratalla E, Watanabe K, Taniguchi T, Manni S, Canfield P, Fernández-Rossier J and Jarillo-Herrero P 2018 Science360 1218
[18]
Wang Z, Gutiérrez-Lezama I, Ubrig N, Kroner M, Gibertini M, Taniguchi T, Watanabe K, Imamoğlu A, Giannini E and Morpurgo A F 2018 Nat. Commun.9 2516
[19]
Ghazaryan D, Greenaway M T, Wang Z, Guarochico- Moreira V H, Vera-Marun I J, Yin J, Liao Y, Morozov S V, Kristanovski O, Lichtenstein A I, Katsnelson M I, Withers F, Mishchenko A, Eaves L, Geim A K, Novoselov K S and Misra A 2018 Nat. Electron.1 344
[20]
Kim H H, Yang B, Patel T, Sfigakis F, Li C, Tian S, Lei H and Tsen A W 2018 Nano Lett.18 4885
Huang B, Clark G, Klein D R, MacNeill D, Navarro-Moratalla E, Seyler K L, Wilson N, McGuire M A, Cobden D H, Xiao D, Yao W, Jarillo-Herrero P and Xu X 2018 Nat. Nanotechnol.13 544
[23]
Wang Z, Zhang T, Ding M, Dong B, Li Y, Chen M, Li X, Huang J, Wang H, Zhao X, Li Y, Li D, Jia C, Sun L, Guo H, Ye Y, Sun D, Chen Y, Yang T, Zhang J, Ono S, Han Z and Zhang Z 2018 Nat. Nanotechnol.13 554
Cai X, Song T, Wilson N P, Clark G, He M, Zhang X, Taniguchi T, Watanabe K, Yao W, Xiao D, McGuire M A, Cobden D H and Xu X 2019 Nano Lett.19 3993
[29]
Klein D R, MacNeill D, Song Q, Larson D T, Fang S, Xu M, Ribeiro R A, Canfield P C, Kaxiras E, Comin R and Jarillo-Herrero P 2019 Nat. Phys.15 1255
[30]
Kim H H, Yang B, Li S, Jiang S, Jin C, Tao Z, Nichols G, Sfigakis F, Zhong S, Li C, Tian S, Cory D G, Miao G X, Shan J, Mak K F, Lei H, Sun K, Zhao L and Tsen A W 2019 Proc. Natl. Acad. Sci. USA116 11131
2020, Vol. 37 
